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5b8e2f61b9
Paolo noticed a cache line miss in UDP recvmsg() to access sk_rxhash, sharing a cache line with sk_drops. sk_drops might be heavily incremented by cpus handling a flood targeting this socket. We might place sk_drops on a separate cache line, but lets try to avoid wasting 64 bytes per socket just for this, since we have other bottlenecks to take care of. sock_rps_record_flow() should only access sk_rxhash for connected flows. Testing sk_state for TCP_ESTABLISHED covers most of the cases for connected sockets, for a zero cost, since system calls using sock_rps_record_flow() also access sk->sk_prot which is on the same cache line. A follow up patch will provide a static_key (Jump Label) since most hosts do not even use RFS. Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Paolo Abeni <pabeni@redhat.com> Acked-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net> |
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